In recent years, aluminum wires have been used for the purpose of weight reduction and the like also in the field of automotive wiring harnesses and the like. An aluminum wire is, for example, structured such that a core formed by twisting a plurality of aluminum strands is covered by an insulation coating, and a terminal fitting is generally connected to an end of the wire when the wire is assembled into a wiring harness. Specifically, an end of the coating of the aluminum wire is removed to expose an end of the core, a wire barrel (wire connecting portion) provided on the terminal fitting is crimped to the exposed end of the core, and an insulation barrel provided behind the wire barrel is crimped and connected to an end of the remaining insulation coating (see, for example, Japanese Unexamined Patent Publication No. 2005-50736). Such a terminal fitting is formed by press-working a metal plate with good electrical conductivity.
However, since the tips of the wire barrel are pushed into between the twisted strands, the core may be broken if the wire barrel is crimped under high compression. Further, in the case of spring back (phenomenon in which each wire barrel is going to be open upward), a ceiling plate portion most subject to a force has a thickness equal to one metal plate described above and, hence, is easily affected by spring back. Particularly, in the case of using an aluminum wire, if spring back occurs in the wire barrel and a stress is alleviated, the core is unlikely to follow the wire barrel, thereby forming a clearance between the core and the wire barrel. Therefore, it may not be possible to obtain desired contact resistance and crimping strength.
The present invention was completed based on the above situation and an object thereof is to eliminate the breakage of a core and reduce the influence of spring back.